Recently, the advent of nanophotonic materials has enabled plasmon stimulated emission in metallic nanoparticles [1]}, [2]}, [3]} and waveguides embedding gaining media
[4]}, [5]}, [6]}, [7]}. Metamaterials (MMs) constitute a promising platform for planar sources of coherent radiation [8]} and for cavity-free lasers operating in the stopped-light regime [9]}, [10]}. Furthermore, MMs embedding subwavelength randomly arranged nanostructures in an amplifying medium are promising for achieving self-organized stimulated emission [11]}, enabling to control the properties of the output beam thanks to stable DSs. This requires the engineering and exploitation of the MM effective nonlinear optical response, which is greatly facilitated by graphene [12]}, [13]}, [14]} because it provides saturated absorption at low peak intensities \(\simeq \)  MW\(/\) cm\(^2\)  [15]}, [16]}, [17]} over a broad spectrum spanning the optical and infrared frequency ranges. This peculiar property of graphene is enabled by its conical band-structure providing resonant interband absorption at arbitrary radiation frequencies, thus greatly facilitating the engineering of the random MM effective nonlinear response [11]}.
